1909.] CRUSTACEA OF THE GENUS GEXXADAS. 725 



Tlie rostral crest (PI. LXXIV. fig. 5), except for the greater 

 prominence of the dorsal and apical spines, agrees closely with that 

 of G. lycirvus. The antennary and infra-antennary angles are both 

 acute : the latter is rather more bluntly rounded than the former. 

 The branchiostegal spine is prominent. The distance between 

 the cervical and post-cervical grooves, measured dorsally, is less 

 than one-third the distance from the post-cervical groove to the 

 hinder margin of the carapace. Both the grooves are faint 

 dorsally and do not interrupt the sti-ong median carina which 

 extends the whole length of the carapace. 



The second joint of the antennular peduncle, measured dorsally, 

 is fully three-quarters the length of the ultimate joint. The 

 antennal scale (PL LXXIY, fig. 9) 'is rather less than three times 

 as long as its greatest width and is remarkable for its extremely 

 narrow apex. The convex outer margin terminates in a rather 

 strong spine, which scarcely reaches as far forward as the 

 lamella. 



The ultimate joint of the mandibular palp (PI. LXXIV. fig. 10) 

 is a little shorter than the width of the basal joint. In the second 

 maxilla (PL LXXIV. fig. 8) the anterior lobe of the internal lacinia 

 is very strongly constricted behind the apex, but is not broader than 

 the adjacent lobe of the external lacinia. The anterior lobe of 

 the latter lacinia is very broad — about twice the width of the 

 interior lobe. The tip of the endopod is long and narrow ; it 

 bears four terminal setaj and four curved dorsal spines behind 

 the apex. The endopod of the first maxillipede reaches a little 

 beyond the exopod. The third joint is practically twice the length 

 of the second, and the fourth joint is extremely minute. The 

 basal joint bears three curved spines on its inner distal mai-gin. 

 The merus of the second maxillipede (PL LXXIV. fig. 7) is lest 

 than twice as long as wide ; the anterior prominence measures 

 about two-sevenths the total length of the joint. 



In the first pair of pereiopods the carpus and chela are of equal 

 length ; each is about two-thirds the length of the merus. In the 

 second pair the palm is almost one and a half times as long as the 

 dactylus, the whole chela being i-ather nioi-e than three-quarters 

 the length of the carpus. The carpus of the third pair is four- 

 fifths the length of the merus ; the chela is exactly half the length 

 of the carpus and the palm is not appreciably longer than the 

 dactylus. 



The sixth somite alone is dorsally carinate. All the abdominal 

 sterna bear a blunt and inconspicuous median tubercle with the 

 exception of the first, which carries a very strong sharply 

 pointed spine in the same position. This character, which is 

 equally definite in both sexes, will probably prove of considerable 

 specific value : it does not seem to occur in any of the species' 

 described by Bouvier. 



The apex of the telson is rounded and furnished with a series 

 of long plumose setfe (eleven in one fairly perfect example). One 

 specimen (PL LXXIV. fig. 11) bears a pair of stovit spines as 



